Re-sampling historical inventory plots indicates degree of forest changes over the last 100 years

Snapshot : A 100 years of forest change is documented. Contemporary forests are compared to their historical counterparts. The findings presented here can be used by managers and ecologists interested in restoring Sierra Nevada mixed-conifer forests.

Summary

In order to document degree of forest change over the last 100 yrs, we re-sampled plots within a 10000 acre area originally inventoried by U.S. Forest Service in 1911. Over half of the area had burned in relatively recent fires. This allowed for comparisons of both areas that have experienced recent fire and areas with no recent fire, to the same areas historically based on early forest inventories. Our results indicate substantially altered present forest conditions, relative to the 1911 data, and can largely be attributed to the disruption of the key ecosystem process for these forests, fire. For areas that burned recently there was a noticeable difference in forest structure based on fire severity. Current tree density and canopy cover in areas burned recently with moderate severity did not differ from 1911 estimates, while areas that burned recently with low severity or unburned sites had higher tree density and canopy cover relative to the 1911 estimates. This emphasizes an important distinction with regard to using fire to restore forests. Moderate severity fire that kills significant understory and intermediate trees came closest to restoring the early stand structure. Our results also demonstrate nearly a doubling of live tree carbon stocks in the present forest compared to the historical forest.